Stabilizing fatty compositions



Patented Junezl, 1941 UNITED STATES PATENT OFFICE George D. Martin, mm.'w. v... assignor to Monsanto Chemical Comp ny, St. Louis, 110., acorporation of No Drawing. Application Jilly 21, ms, x Serial No.285,761

a claims. (c1. zs-zso) a This invention relatesto the treatment-of oilscontaining a fatty component and more particularly to the treatment ofanimal, vegetable and flshoils for the purpose of inhibiting rancidityand other undesirable eflects'associated therewith.

Animal, vegetable, ilsh and the like oils are fatty acid esters, as,fOr'e-x'ample fatty acid glycerides. As is well. known, oils .of thistype are subject to changes characterized by the formation ofmalod'orous products which render them unsuitable for foodstuffs and formany other.

purposes. This condition is commonly referred to. as rancidity. Wherethe fatty acid compo nents of the oil comprise an unsaturated conriallyenhanced. Rancidity is believed to result from the formation ofaldehydes, ketones. peroxides andv similar oxidative degradationproducts of the oil and is usually further characterized by a bleachingaction due to the peroxide content. For example olive oil is normallythe familiar light golden color-whereas therancid product is colorlessand possesses a decidedly unpleasant taste and odor. e transformation tothe latter condition is accelerated by heat, light and various chemicalagents and in general special precautions are necessary in handling andstoring vegetable, animal .and fish 'oils, especially where intended forhuman consumption.

It is an object of this invention to stabilize vegetable, animal, fishand the like oils and more particularlyto prevent the development ofranv L One of the specific objects of this invention is to provide arancidity inhibiting or retardin stituent the susceptibility, torancidity is mate- Typical examples of the preferred classof'stabilizers comprise tri o-phenylene phosphate of.

the formula several days in an oven maintained at 50 C.

After various intervals of time the aged samples are tested in a manneranalogous to that described-by D. H. Wheeler, Oil and Soap, Vol. 9, page93, 1932. Thus, iive grams of the oil are dissolved in 50 c. c. ofsolvent mixture (60 percent of glacial acetic acid, 40 percent ofchloroform) and 1 c. c. of saturated potassium iodide agent to beincorporated with the oil which is to be stabilized. A further obiect isto provide and oil composition stabilized against the development ofrancidity. Other and further objects will be hereinafter shown. v

In accordance with present invntion it has been discovered that theneutral phosphates of polyhydric phenols are highly effectivestabilizers of oils containing a fatty component. Estersof inorganicacids in which the inorganic acid nu- ,cleus is completely esterified,i. e. no replaceable hydrogen remains, are commonly termed"neutralesters" and it is'ln this sense that the term neutral is hereinemployed.

The preferred esters may be prepared by known methods from suitableesterifying agents solution added. After exactly oneminute from the timeof the addition of potassiumiodide. 100 c. c. of water are added and theliberated iodine titrated with-0.0m sodium thiosulfate, cmploiing starchas indicator. Thetitration in cubic centimeters is a measure of theperoxide formation and consequently a measure of Y the stability of theoil. The so calledperoxide.'number" which is the usual basis 'ofcomparison is defined by Wheeler according to the equation 'T NX-500 M WI I where W is the. weight of j the oil and T is the milliters ofthiosulfate of normality N. M is thus the millimols of-peroxide perkilogram or the peroxide number. '(See also CJH. Lee,

such as P201; and P001: and a polyhydric phenol.

- Neutral'phosphates derived from catechol, tertiary amyl catechol,tertiary butyl c'atechol, chlor catechol. pyrogallol, resorcincl,hydroquihone,-

' hydroxy hydroquinone 3,4 dioxy biphenyl. p,p'

dioxy biphenyl, 3,4,4 trio'xybiphenyl, 1,2 ;di oxy naphthalene, 1,5dioxynaphthalene and ,the'like are included within the scope of thisinvention.

Rancidity in Edible Fats, page 108.) Obviously where a 5 gram sample ofoil is titrated with .01Nthiosulfate the milliters required give theperoxide number directly.

I The followingare specific embodiments of the invention showing theuseful and valuable properties of the preferred class of stabilizers andare to be understood as illustrative of the invention but innowise'limitatwe thereof. r ,A small proportion, 0.1% of the stabilizingagent, was incorporated into an unstable oil. The peroxide number wasdetermined as described above and compared with the untreated oil. iTypical results obtained upon testing the preferred class of neutralesters are set forth below:

Peroxide num- Cottonseed oil stabilizing agent be: after 30 a y as s Trii-hydroxy o-phenylene phosphate 6.0 Trl 3-1: droryohenylene; hosghste2.0 Tri 4-K any] o-p {lump osp ate. 1.0 Tri 6- ydroxy l-napthyl)phosphate- 0.6 Blank 390.0

As further illustrative of the desirable properties of the preferredclass of stabilizers, the peroxide numbers of typical oils stabilized bythe addition of 0.1% of tri(o-phenylene) phosphate as compared with theperoxide number of the untreated oil (Blank) are given below.

Peroxide numbers after aging ior- Oil 10 days Cottonseed 8 an!(cottonseed) The following data show the peroxide numbers of oleic acidstabilized with 0.1% or tri(4- "tertiary amyl o-phenylene)phosphate ascompared with the untreated product.

Peroxide nnrfnbers after aging or 21 days 34 days 53 days Treatedproduct 2. 7 1. 4 E. Blank.-. 21.0 24.0 29. 7

2,247,2ao V From the data set forth above it is shown that thepreferredstabilizing agents possess exceptional rancidity inhibitingproperties when incorporated in unstable oils, as for example animal,vegetable and fish oils.

The amount of stabilizing agent which may be added'to an unstable oilmay be varied within wide'limits but in general it will be found thatgood results may be obtained by adding, upon a weight basis from 0.01%to 1.0% of the stabilizing agent.

Other-methods of testing the stability of unstable oils than thosespecifically disclosed may 'Ffrom 0.01% to 1.0% of a be employed as iswell known to those skilled in the art to which the present inventionpertains.

The present invention is limited solely by the following claims attachedhereto as part of the specification.

What is claimed is:

1. A fatty oil having incorporated therein a neutral phosphate of apolyhydric phenol in an amount sufficient to preserve said fatty oil.

2. A fatty oil havingincorporated therein a tri (o-arylene) phosphate inan amount sufficient to preserve said fatty oil.

3. A fatty oil having incorporated therein a tri (o-phenylene) phosphatein an amount sufficient to preserve said fatty oil.

4. A fatty oil having incorporated therein tri (4-tertiary amylo-phenylene) phosphate in an amount sufficient to preserve said fattyoil.

5. A fatty oil having incorporated therein tri (4-hydroxy l-naphthyl)phosphate in an amount suflicient to preserve said fatty oil.

-6. A: fatty oil havingincorporated therein neutral phosphate of apolyhydric phenol I r GEORGE D. MARTIN.

